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Thermal Inactivation Kinetics Of Salmonella In Milk Powder As Impacted By Water Activity And Powder Type, Erika Litta Kadas
Thermal Inactivation Kinetics Of Salmonella In Milk Powder As Impacted By Water Activity And Powder Type, Erika Litta Kadas
Graduate Theses and Dissertations
Historically, low-water activity (aw) foods (aw <0.65) were considered to be microbiologically safe for consumption. However, these foods have been implicated in outbreaks of pathogens such as Salmonella enterica, at a frequency that surely challenges this assumption of safety. Although usually implicated in outbreaks involving poultry and egg products, Salmonella spp. have frequently been the culprit in several outbreaks and recalls associated with low-water activity foods (LWAF) due to contamination resulting from the environment, animals, or even the employees during pre-or post-processing. One such LWAF that has been associated with Salmonella spp. outbreaks is milk powder. Milk powders are used in a variety of products ranging from infant formula to confectionary goods. With their widespread use, improving their safety is imperative. A key step in improving their safety is to thoroughly investigate preventive controls related to milk powder processing. The Food Safety Modernization Act (FSMA) established the Preventive Controls for Human Foods Rule, which mandates that processors design and establish a food safety plan outlining any potential hazards and the steps they will take to ensure those hazards do not compromise the safety of the product. Presently, the dairy industry does not have an established kill-step for milk powders post-spray drying. Spray drying may reduce some microbial populations, however, desiccation(e.g., spray drying) is not considered a kill-step. The work outlined in this thesis aims to assist our dairy industry partners in establishing their own thermal process for milk powders post-spray drying. Moisture sorption isotherms of two milk powders (nonfat dry milk: NFDM and a milk protein concentrate with 85% protein content: MPC-85) were determined and showcased that the temperatures at which the isotherms were determined (23, 40, or 60°C) significantly affected both the adsorption and desorption isotherms (p<0.0001) for each powder. Secondly, the thermal inactivation kinetics of Salmonella spp. in both powders were evaluated at two different water activities (0.20 and 0.30) and three temperatures (75, 80, and 85°C) to determine the effect of water activity on the thermal resistance of a cocktail of Salmonella spp. The D-values of Salmonella were heavily influenced by the thermal treatment temperature (p< 0.0001), but not the water activity (p >0.05). The overall findings contained within this thesis provide valuable information about the thermal inactivation kinetics of Salmonella spp. to our partners in the dairy industry so that they may implement an appropriate thermal process for their milk powders.
To The Window, To The Wall: Improving Environmental Monitoring Protocols, Sarah Jones
To The Window, To The Wall: Improving Environmental Monitoring Protocols, Sarah Jones
Graduate Theses and Dissertations
Detecting microorganisms on environmental surfaces via an environmental monitoring (EM) program is part of a preventive food safety culture. Environmental monitoring should 1) verify that food safety plans are reducing cross-contamination risk from surfaces to food, 2) pinpoint microbial niches, and 3) prevent the transmission of pathogens. Environmental monitoring programs utilize EM tools, such as sponges, to sample food contact and non-food contact surfaces. However, EM tool selection is determined by the individual food firm. This dissertation evaluated and characterized factors influencing EM program effectiveness in the food industry. Specifically, this dissertation focuses on the release of microorganisms from EM …
Fate And Dissemination Of Salmonella Reading In Market-Age Turkeys At Processing Using Oral Gavage Challenge Model, Aaron Ashcraft
Fate And Dissemination Of Salmonella Reading In Market-Age Turkeys At Processing Using Oral Gavage Challenge Model, Aaron Ashcraft
Graduate Theses and Dissertations
This study aimed to evaluate the fate and dissemination of Salmonella Reading (SR) in market-age turkeys using an oral gavage challenge model. One hundred twenty-eight-week-old commercial turkey hens were moved from commercial production to research facilities. Upon arrival, a combination of enrofloxacin, 10 mg/kg, and florfenicol, 20 mg/kg, were orally administered sequentially before comingled placement on fresh pine shavings. Turkeys were challenged with 108 cfu SR by oral gavage on days 4 and 7 post-placement. Subsets were subjected to simulated commercial processing on days 14 (n=40), 21 (n=40) and 28 (n=32) post-placement (corresponding to 10, 11, and 12 weeks of …
Food Safety Risk In An Indoor Microgreen Cultivation System, Gina Marie Misra
Food Safety Risk In An Indoor Microgreen Cultivation System, Gina Marie Misra
Graduate Theses and Dissertations
Microgreens are immature sprouts of edible plants, sharing some similarities with sprouted seeds and petite leafy greens. Since they are most often grown in containers in buildings or greenhouses, they present a new area for food safety research at the intersection of the built environment and produce farming. Contamination by human pathogens has been extensively studied in other types of produce typically eaten raw, including sprouted seeds, which have been implicated in numerous outbreaks of salmonellosis over the last several decades. There is a paucity of knowledge about the microgreen sector of the fresh-cut industry; thus, it was determined that …
The Impacts Of Administering Metabolites Of Saccharomyces Cerevisiae On Broiler Performance, Yields And Salmonella Content Of Component Portions, Bill Douglas Potter
The Impacts Of Administering Metabolites Of Saccharomyces Cerevisiae On Broiler Performance, Yields And Salmonella Content Of Component Portions, Bill Douglas Potter
Graduate Theses and Dissertations
The impacts of using health-promoting Saccharomyces cerevisiae fermentation metabolites in poultry production and processing can be measured in respect to multiple measures of success. Traditionally this yeast-based compound has been administered to poultry, livestock, poultry, and other species to improve animal performance and production volume output. In addition, Saccharomyces cerevisiae fermentation metabolites have also been shown in more recent research to reduce colonization of pathogenic bacteria in the host organism’s gastro-intestinal tract. In this dissertation, the impacts of administering a functional ingredient containing Saccharomyces cerevisiae metabolites on broiler performance measures and pathogen reduction were measured. One of the studies in …
Assessment Of Salmonella Enterica Biofilms And Expression Differences Among Serovars, Zhaohao Shi
Assessment Of Salmonella Enterica Biofilms And Expression Differences Among Serovars, Zhaohao Shi
Graduate Theses and Dissertations
Biofilms are communities of microorganisms associated by a matrix of extracellular polymers. In this state, microorganisms occupy an ecological niche distinct from their free-floating, planktonic counterparts. Also, biofilm bacteria become biologically unique as they form communities and lose motility. The acquisition of these physiological attributes enables the biofilm to persist through harsh environmental conditions, including antimicrobial induced stress and to resist sanitization efforts. Because of these features, biofilms can rapidly disseminate across numerous surfaces and as they establish, become challenging to remove. This is a particular issue for the food industry as processing plants offer favorable conditions for biofilm formation …
Experimental Approaches To Understand And Control Salmonella Infection In Poultry, Yichao Yang
Experimental Approaches To Understand And Control Salmonella Infection In Poultry, Yichao Yang
Graduate Theses and Dissertations
Salmonella is a major foodborne pathogen around the world and chickens are the major reservoir to transmit Salmonella into the human food chain. For decreasing the infection of Salmonella, we developed six attenuated live vaccines based on Salmonella Enteritidis (SE) and Typhimurium (ST) for testing the cross-serovar and cross-serogroup protection from the challenge of Salmonella Heidelberg and Campylobacter jejuni. One of the constructed vaccine strain showed ability to protect against challenge from Salmonella Heidelberg. Even though some preventive approaches are able to decrease Salmonella colonization in the gastrointestinal tract of chickens or other farm animals, Salmonella transmission mechanisms remain unclear. …
Role Of Incompatibility Group 1 (Inci1) Plasmid-Encoded Factors On Salmonella Enterica Antimicrobial Resistance And Virulence, Pravin Raghunath Kaldhone
Role Of Incompatibility Group 1 (Inci1) Plasmid-Encoded Factors On Salmonella Enterica Antimicrobial Resistance And Virulence, Pravin Raghunath Kaldhone
Graduate Theses and Dissertations
Foodborne illnesses are a leading cause of infectious diseases in the world. Among enteric organisms Salmonella is a key pathogen. It’s high prevalence in poultry and other food-animal sources make it imperative to study. Salmonella has the ability to modify its genetic content with help of mobile genetic elements such as plasmids. Incompatibiltiy group 1 (IncI1) plasmids are commonly reported in Salmonella. This study evaluates role on IncI1 plasmids in antimicrobial resistance and virulence in Salmonella. Genetic determinants of resistance and virulence are noted among our IncI1-containing Salmonella isolates. These genetic elements are also transferable and reported to carry respective …
A Molecular Approach To Understanding The Effects Of Original-Xpc On The Modulation Of The Cecal Microbiota And The Survival Of Salmonella In The Poultry Host, Stephanie Roto
Graduate Theses and Dissertations
Salmonella is a foodborne pathogen commonly associated with poultry products; the economic burden to the U.S. is estimated to be approximately $693 million (without factoring in contaminated eggs). Recently, there has been pressure to withdraw sub-therapeutic levels of antibiotics (also known as antibiotic growth promoters; AGP) from poultry due to concern over antibiotic-resistant bacteria spreading to the human population. Therefore, various feed additives have been researched for their ability in providing protection against harmful pathogens and their potential growth promoting effects, both of which were attributes of poultry treated with AGP. This thesis consists of a comprehensive literature review that …
The Effects Of Electrostatic Spraying With Organic Acids In The Disintegration Of Biofilms Formed By E.Coli O157:H7 And Salmonella Typhimurium On Spinach And Cantaloupe, Ahmad Almasoud
Graduate Theses and Dissertations
Outbreaks from the consumption of fresh produce are a concern in the United States. The consumptions of fresh produce have increased recently which expose a large segment of society to such outbreaks. Spinach and cantaloupe are minimally heated or processed before consumption which makes them a possible source of foodborne illness. The objective of this research was to investigate the effect of organic acids alone and in combination to reduce attached Salmonella Typhimurium (S.T) and Escherichia coli O157:H7 (E.coli) on spinach and cantaloupe, and to disintegrate biofilm formed by these pathogens by electrostatically spraying with two organic acids. To quantify …
Phenotypic And Functional Genomics Analyses Of Salmonella For Food Safety Applications, Turki Dawoud
Phenotypic And Functional Genomics Analyses Of Salmonella For Food Safety Applications, Turki Dawoud
Graduate Theses and Dissertations
Non-typhoidal Salmonella species have been major foodborne zoonotic pathogens causing serious problems in public health and food industry for several decades. Numerous Salmonella species have frequently been associated with different food commodities mainly poultry meat, eggs, and their products. This dissertation begins with a literature reviews discussing many aspects of Salmonella generally; and subsequently focused on two serotypes, Salmonella Enteritidis and S. Typhimurium as they are at the top of all other serovars responsible for most illness cases and outbreaks. In addition, some Salmonella strains have exhibited their ability to tolerate and survive many food processing treatments. We can divide …
Phenotypic, Physiological And Growth Interactions Among Salmonella Serovars, Juliany Rivera Calo
Phenotypic, Physiological And Growth Interactions Among Salmonella Serovars, Juliany Rivera Calo
Graduate Theses and Dissertations
This thesis consists of four research parts: a literature review that covers Salmonella spp., one of the more prominent foodborne pathogens that represents a major risk to humans (chapter 1). Understanding the growth of Salmonella serovars and strains is an important basis for more in depth research. In this case we studied a) the aerobic and anaerobic growth responses of multiple strains from six different serovars, b) how the spent media from different serovars, more importantly S. Heidelberg, affect the growth of S. Typhimurium, and c) determined whether or not two different serovars undergo competitive interactions when they were …
Electrostatic Spray Application Of Food-Grade Organic Acids And Plant Extracts To Decrease Escherichia Coli O157:H7 And Salmonella Typhimurium On Select Produce, Leighanna Maeree Massey
Electrostatic Spray Application Of Food-Grade Organic Acids And Plant Extracts To Decrease Escherichia Coli O157:H7 And Salmonella Typhimurium On Select Produce, Leighanna Maeree Massey
Graduate Theses and Dissertations
Both consumers and suppliers have been negatively affected by an increase in foodborne pathogens contaminating fruits. Consequently, there is a need for the development of more efficient antimicrobials and application techniques to decrease contamination. Natural preservatives such as organic acids and plant extracts have demonstrated promising results in decontaminating produce. In addition, the effectiveness of such preservatives may be enhanced by the use of an electrostatic sprayer. The objective of this research was to determine the combinations and concentrations of organic acids and plant extract that were able to reduce Salmonella Typhimurium (ST) and Escherichia coli O157:H7 (EC) inoculated fruits …